Inhalable anesthetics (which are alternatively described as anesthetic agents) are typically volatile substances with relatively low boiling points and high vapor pressures. They can be flammable and explosive substances in both their liquid and vapor states. Further, inhalation of the vapor by health care personnel can cause drowsiness.
Therefore, such anesthetics must be safely handled in operating rooms in order to minimize the risk of inhalation by medical personnel as well as to minimize the risk of fire or explosion. Preferably, the anesthetic should be used in a way which will ensure that there is little or no release to the atmosphere at all stages of handling.
Anesthetics are typically dispensed in liquid form to an apparatus, such as an anesthetic vaporizer, which mixes the anesthetic with oxygen and nitrous oxide. The mixture is supplied in gaseous form to the patient for inhalation.
Devices have been designed for the transfer of an anesthetic from a supply container to a vaporizer through a closed system that minimizes the likelihood of the escape of an anesthetic gas to the atmosphere. The devices are designed so that during set-up and disassembly procedures, a supply container of anesthetic is not open and exposed to the atmosphere.
One system which has been developed for connecting an anesthetic container to a vaporizer is the SECURITY LOCK.sup..TM. Vapofill vaporizer connector sold by Abbott Laboratories, Inc., One Abbott Park Road, Abbott Park, Ill. 60064-3500, U.S.A. and Abbott S.p.A., 04010 Campoverde, Latina, Italia. It may be disposable, and it employs a connector tube having special connecting or coupling members at both ends. The tube is flexible and is kink-resistant. The vaporizer end of the tube is provided with a vaporizer connector, adaptor, coupling member, or pin that engages an anesthetic vaporizer. This can be initially closed with a removable cap. The end of the tube attached to the anesthetic container is provided with a closure adaptor that engages a closure on the anesthetic container.
The closure is preferably connected to the anesthetic container prior to use. The container closure has a frangible seal adapted to be perforated by a piercing means within the closure adaptor as the adaptor engages the closure. Following perforation of the frangible seal by the piercing means, the closure adaptor and closure remain locked together, and this permits the transport of anesthetic through the tube from the supply container to the vaporizer. The system remains closed to the atmosphere throughout the assembly or disassembly procedures.
While the above-described SECURITY LOCK.sup..TM. transfer system is effective in transferring a liquid anesthetic agent to the vaporizer, the operator must properly dispense the anesthetic into the vaporizer in a manner that avoids overfilling the vaporizer beyond a maximum level. This may be accomplished in various ways, such as by ascertaining the level of anesthetic, if any, existing in the vaporizer and dispensing the anesthetic from a supply container having a quantity of anesthetic that will not overfill the vaporizer. Alternatively, where a large supply of anesthetic is provided in the container, the filling process can be monitored so that the filling process can be terminated when the anesthetic in the vaporizer has reached the desired maximum level (e.g., such as can be seen on a sight glass connected to the vaporizer).
While such processes function well when properly executed, it would be desirable to provide an improved system which would be more convenient and which would eliminate the need for careful monitoring by the operator. In particular, it would be advantageous if such an improved system could provide a process for positively stopping the filling of the vaporizer at a predetermined level, regardless of the quantity of anesthetic agent in the supply container.
It would also be advantageous if such an improved system employed container components and structures that could accommodate storage of the anesthetic during a relatively long shelf life without the container structures being degraded to an extent that might deleteriously affect subsequent use of the container to fill the vaporizer.
Further, it would be desirable to provide such an improved system that can accommodate designs significantly minimizing the likelihood of spillage or leakage while at the same time accommodating a relatively rapid filling of the vaporizer.
Some types of vaporizers are intended for use with only a specific anesthetic. In such situations, care must be taken to insure that only the proper anesthetic is dispensed into the particular vaporizer. To this end, the above-discussed SECURITY LOCK.sup..TM. device has been provided with a keying system to prevent the use of the device with an anesthetic for which it is not designed.
In particular, the anesthetic container closure has a specific shape, and the connector tube closure adaptor has a complementary shape for mating with the container closure. At the other end of the container tube, the pin has a special shape for mating with a complementary portion of the vaporizer anesthetic inlet port.
Vaporizer manufacturers provide standard inlet port configurations. These are standardized to I.S.O. ("International Standardization Organization") configurations specific to various types of anesthetics. Because the container for each type of anesthetic has its own special closure shape and color, and because the corresponding connector device fits only the type of vaporizer designed for that type of anesthetic, the probability of inadvertently using the wrong type of anesthetic in a vaporizer is greatly reduced.
Although such keyed, connector tubes function satisfactorily, there are inventory, installation, operation, and management requirements and considerations associated with their proper use. It would be desirable to minimize such requirements and considerations. In particular, it would be advantageous to provide a system with improved connection structures or engagement structures for minimizing the likelihood that the container can be improperly connected at the vaporizer. Such an improved system should facilitate the formation of a connection that is not susceptible to leakage of the anesthetic liquid or vapor.
The present invention provides an improved anesthetic transfer system which can accommodate designs having the above discussed benefits and features.